Here are some good reasons to read this book:
You need a quick reference for practical, security-related tasks.
You think your system is secure, but haven't done much to check or ensure this. Think again. If you haven't followed the recipes in this book, or done something roughly equivalent, your system probably has holes.
You are interested in Linux security, but fear the learning curve. Our book introduces a quick sampling of security topics, with plenty of code for experimenting, which may lead you to explore further.
The book is primarily for intermediate-level Linux users. We assume you know the layout of a Linux system (/etc, /usr/bin, /var/spool, and so forth), have written shell and Perl scripts, and are comfortable with commands like chmod, chgrp, umask, diff, ln, and emacs or vi. Many recipes require root privileges, so you'll get the most out of this book if you administer a Linux system.